After Omicron infection, risk of BA.2 is rare, says study

Source From: ENT 2022-02-27 10:12:49

People infected with the highly contagious Omicron variant of Covid are less likely to contract BA.2 subvariant, according to a study.

Omicron, which has rapidly spread worldwide, carries numerous mutations in key regions and is associated with increased transmissibility and immune escape.

The variant has recently been divided into three subvariants with substantial genomic differences, in particular between Omicron BA.1 and BA.2.

While Omicron is on the decline, many countries in Europe and Asia have seen an increase in BA.2 cases.

With the surge in BA.2, a large number of reinfections from earlier cases has been observed, raising the question of whether the subvariant specifically can escape the natural immunity acquired shortly after a BA.1 infection.

"We provide evidence that Omicron BA.2 reinfections do occur shortly after BA.1 infections but are rare," said corresponding author Morten Rasmussen, from the Department of Virus and Microbiological Special Diagnostics, at Statens Serum Institut, Denmark.

While the reinfection rate appears to be low given the high number of positive SARS-CoV-2 tests during the study period, it "still highlights the need for continuous assessment of length of vaccine-induced and/or natural immunity", Rasmussen said.